Bruce - Yes, I've used them a number of times for replacement parts including the circuit board for my old Powerdrive V2 TM. I love their parts diagrams and had the part(s) I needed in stock. Replaced my steering drive assy not too long ago also.
They do make rebuild kits plus the gears are available for purchase. But in my opinion, by the time you buy the parts along with possible shipping charges not to mention what your time is worth to tear it apart & rebuild it - might be better off just buying the assembly. That's what i did.